nginx代理+keepalived双机热备

利用keepalived+nginx实现官网web的高可用性
两台服务器一台为主，一台为备机，使两台机器公用一个虚拟IP，当主服务器宕机，这个IP会自动切换到备机上，前端机恢复之后再自动切换回主服务机。

主和辅都需要安装keepalived,安装方法相同
yum -y install  kernel-devel
yum install openssl-* -y
wget http://www.keepalived.org/software/keepalived-1.2.2.tar.gz
tar xzf keepalived-1.2.2.tar.gz
cd keepalived-1.2.2
./configure --prefix=/usr/local/keepalived
make && make install
ln -s   /usr/src/kernels/2.6.32-431.23.3.el6.x86_64/ /usr/src/linux #注意系统位数
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
mkdir -pv /etc/keepalived
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
ln -s /usr/local/keepalived/sbin/keepalived /sbin/

加入开机启动：chkconfig keepalived on

二、配置
主和辅配置的差别只在stateMASTER和priority 100
vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
#  notification_email {    ####此处定义发生替换会邮件通知
#    [e-mail]
#  }
#  notification_email_from [e-mail]
#  smtp_server 127.0.0.1
#  smtp_connect_timeout 30
  router_id LVS_DEVEL
}

vrrp_script chk_http_port {
                script "/root/shell/nginx_pid.sh" ##监控脚本位置
                interval 2
                weight 2
}
track_script {
      chk_http_port
      }
vrrp_instance VI_1 {
    state MASTER        #####备机为BACKUP
    interface eth0 
    virtual_router_id 51
    priority 100        #####备机要小于主
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress { 
        192.168.1.68  ####虚拟IP
    }
}

#!/bin/bash
A=`ps -C nginx --no-header |wc -l`           
if [ $A -eq 0 ];then                                   
                /usr/local/nginx/sbin/nginx
                sleep 3
                if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
                      killall keepalived
                fi
fi

nginx的 配置这里就不写了配置太多了！

如果是双网卡可以参考：http://blog.csdn.net/jiedushi/article/details/6097920